When a tool is inserted into a hole formed in a workpiece to polish the inner circumferential surface of the hole or to deburr the edge of another hole intersecting with the above-mentioned hole, a rotating tool including grinding members at the front end thereof is employed. Patent Literature 1 describes a rotating tool including a plurality of linear grinding members, a grinding member holder to bundle the rear ends of the plurality of linear grinding members, and a shank extending backward coaxially from the grinding member holder.